OAPEN is an online library that currently holds 2,500 open-access scholarly books. The site is maintained by the OAPEN Foundation, a non-profit organization established by a coalition of Dutch universities and libraries that is based out of the National Library in the Hague. The OAPEN Foundation collaborates with 100 publishers from eighteen different countries, including many universes presses, in order to provide librarians, researchers, and the general public with peer reviewed books about a variety of subjects. Users can browse through books by subject or filter by language. (The majority of books on this site are in English, although many are in Dutch, French, and Italian as well. Twenty-three languages are represented in total). While OAPEN includes items across all academic disciplines, the majority of books available on this site are in the social sciences and humanities. The collection is continuing to grow and users can subscribe to a newsletter to receive updates.